2x的四次方-x的立方-6x的平方-x+2
=2x^4-4x³+3x³-6x²-x+2
=2x³(x-2)+3x²(x-2)-(x-2)
=(x-2)(2x³+3x²-1)
=(x-2)[2x³+2x²+x²-1
=(x-2)[2x²(x+1)-(x+1)(x-1)]
=(x-2)(x+1)(2x²-x+1)